Lighting device



Oct. 13, 1964 J. WETZEL LIGHTING DEVICE Filed Jan. 31', 1962 am n '7panying drawing wherein: FIGURE 1 is a front v1ew with parts brokenaway, illustrating a lighting device according to this invention;

United States Patent LIGHTING DEVICE Joseph Wetzel, 108 Ave. DenfertRochereau, Paris, France, assignor of one-half to Anciens EtablissementsTuzet, Paris, France, a socit anonyme Filed Jan. 31, 1962, Ser. No.170,207 Claims priority, application France, Feb. 3, 1961,

851,582, Patent 1,287,572 2 Claims. (Cl. 240-4629) This inventionrelates in general to lighting devices and has specific referencetodevices of this character wherein the intensity of the emitted light canbe gradually increased and decreased through simple yet efficient means.

As a rule, the light emitted from electric lamps is gradually increasedand decreased by adjusting the intensity of the current passing throughthe lamp filament or filaments by means of rheostats or variable chokes,with these conventional means the illumination of the different surfacesreceiving the light vary in proportion tothe intensity of the lightsource and their uniformity remains constant. t

In the device constituting the subject-matter of this invention theintensity of the light source remains fixed and the light gradation isobtained by means of shutters displaceable across the light beam. Thus,the costly and cumbersome apparatus necessary for regulating theelectric current applied to the lamps can be dispensed with. I

It is already known to utilize screens for absorbing or blocking onefraction of the light emitted by a light source, but under suchconditions that when said screens are moved across the light beam thearea of the illuminated surface or the uniformity of the illuminationare modified, for example in the specific case of theatre stagelighting.

Light gradation as obtained with the device of'this invention willpractically not impair or change the extent of the illuminated surfacewhile maintaining at all the vpoints ofthis surface the desireduniformity of the illumination.

It is another advantageous feature of this invention to maintainthemcomposition of the lamp radiation and therefore the light color.

This result is obtained by combining into a same device a linear lightsource, a lighting apparatus designed to give parallel and also linearimages of the light source,

and a system of movable shutters adapted, from the very opening of thescreen system, to permit the passage of the light rays issuing from allthe points of the light source and the images formed by the lightingapparatus,

' so that these rays cross one another in a slit formed by icedirection. A cylindrical reflector 5 disposed behind the lamp 2 andcoaxial with the filament 3 reflects toward the axis the light raysemitted backwards. With this optical system a rectangular light beamcharacterized by a considerable width and capable of covering arectangular surface is obtained.

According to this invention, two semi-cylindrical movable shutters 6a,6b coaxial with the filament 3 of the lamp are disposed between the lamp2 and the blades 4. Their length is calculated with a view to block thelight beam completely when they contact each other centrally of theprojector (as shown in chain lines in FIG. 1). These screens areconnected to nuts 7 engaging leading screws 8a,-8b having oppositethreads whereby when these screws are rotated the shutters 6a, 6b aregradually moved away from or towards each other. Thus, a slit 15 isformed in the centre which widens gradually and permits the passage,immediately as the opening movement begins, of a constant-height lightbeam of relatively great width. On the other hand the intensity of thebeam which is zero initially increase-s gradually as the slit widens, toreach a maximum intensity when the screens are retracted completely onthe sides (as shown in dashed lines).

The two leading screws may consist of a single threaded rod 8 having twooppositely threaded portions 8a, 8b.

The screw 8 is rotatably driven from a small electromotor 9 through agear reduction unit 10 comprising for example two pinions of modulus 1and two pinions of modulus 10, all made of Celoron (RegisteredTrademark) or like material (resin-impregnated fabric).

The motor 9 is disposed coaxially with the lamp filament (see FIG. 3)and drives a fan 14 for cooling the projector (FIG. 1).

The leading screw 8 is housed in a rear casing 11 of the apparatus andthe bottom 12 of this casing is detachable to permit the inspection andmaintenance thereof.

Limit-switches, ON and OFF switches, and signalling switches (not shown)may be provided according to the known practice; preferably theseswitches are responsive to theleadingscrew and nuts, and mounted in therear casing 11 where they can be inspected or repaired when necessary. V

The front central portion of the projector is closed by a detachableglass window 13 permitting the passage of FIGURE 2 is a cross-sectiontaken upon the line 11-11 1 p of FIG. 1; and

FIGURE 3 is another cross section taken upon the line III-III of FIG. 1.

the light beam and the replacement of the filament lamp 2.

The projector sides are closed by plates 1 detachable notably on theside of theelectromotor 9 to permit regular inspection and maintenanceof the mechanical components of the apparatus.

The gradual increase and decrease of the light intensity is obtained byremote control means associated with the electromotor whereby the lattercan be rotated in either effect. Color screens may be mounted in frontof the: I V

projector, if desired. e

The light graduation may be regulated with this device from a controlboard comprising push-button switches for controlling the lamps 2 of theprojectorsand the motors 9 operating the shutters 6a and 6b. Thiscontrol board may have relatively small dimensions and can easily bemounted at any desired location for controlling the lighting. I V

The above-described device meets the requirements for producing asimultaneous and gradual increase or de- 3 crease of the illumination atall the points of a givensurface, since from the very beginning of theopening movement of shutters 6a, 6b the slit 15 receives crossed lightrays directed downwardly and from right to left, and issu-, ing from thewhole length of the filament 3 either directly or after being reflectedby the blades 4 and reflectors 5. Thus, the surface'to be illuminatedis.covered completely by the light rays. As the slit 15 widens out agreater number of rays are distributed over the surface, thus ensuring agradual increase of its illumination.

Other optical devices may be imagined without departing from the basicprinciples of this invention. Thus,

for example, the blades 4 may be mounted behind the lamp 2 and sodisposed that they are tangent to an envelope surface of substantiallycylindrical configuration of which the axis is coincident with the lampfilament 3. It is also possible to substitute this reflectingcylindrical surface for the blades, the cross-section of this surfacebeing of parabolic configuration in this case if it is desired stronglyto concentrate the light. In all cases the essential requirement to bemet is that the light source be linear and of relatively great length,and that the optical device reflects or refracts the light rays in sucha manner that the rays are issued from images parallel to the filament.The movable screens should be so designed that as they move away fromeach other the light beam is gradually allowed to pass therebetween,symmetrically in relation to the mesial plane of this beam.

The above-mentioned shutters may be replaced by shutters so disposed asto block the light beam when it leaves the projector. They are movedtowards and away from each other under the control of means similar tothose described hereinabove.

The same dispositions are applicable to systems incorporating electricdischarge tubes, notably fluorescent tubes, and in general to any lightsource of relatively great length, the screens being so disposed as togradually uncover the light rays emitted by the different points of vthe linear light source.

conjunction with preferred embodiments, it is to be understood thatmodifications and variations may be resorted to without departing fromthe spirit and scope of the invention, as those skilled in the art willreadily understand. Such modifications and variations are considered tobe withinthe purview and scope of the invention and appended claims. I

cal edges, said shutters being slidably mounted on a single horizontalaxis in said housing for movement toward and away from each other so as'to define an adjustable slit opening between the adjacent verticaledges for permitting the passage of said beam of light in conform thegradation is obtained bymore or less uncovering a variable surface ofthe diffusing glass. Under these conditions, a single shutter uncoveringthe diffusing surface from one of its ends may be substituted for thetwo shutter halves 641 and 6b.

Although the present invention has been described in ance with the sizeof said slit opening.

2. An incandescent lighting device comprising a support housing, anelongated light bulb having a horizontal axis and mounted in saidhousing for projecting a beam of light, reflector means positioned insaid housing behind said light bulb in spaced parallel relation to saidhorizontal axis of the bulb, a pair of substantially identicalsemi-cylindrical lightblocking shutters in front of and coaxial withsaid elongated light bulb and in spaced parallel relation to saidhorizontal axis of the bulb and having adjacent vertical edges, saidshutters being slidably mounted on a single horizontal axis in saidhousing for movement toward andnaway from each other 'so as to define.anadjustable slit opening between the adjacent vertical edges, andadjustment means operatively connected to said shutters for increasingand decreasing the aperture size of said slit opening such that a beamof light is permitted to pass in conformance with said aperture size.

References Cited in the file of this patent V UNITED STATES PATENTS

1. IN AN INCANDESCENT LIGHTING DEVICE INCLUDING A SUPPORT HOUSING, ANELONGATED LIGHT BULB HAVING A HORIZONTAL AXIS AND MOUNTED IN SAIDHOUSING FOR PROJECTING A BEAM OF LIGHT, REFLECTOR MEANS POSITIONED INSAID HOUSING BEHIND SAID LIGHT BULB IN SPACED PARALLEL RELATION TO SAIDHORIZONTAL AXIS OF THE BULB, AND LIGHT BLOCKING MEANS IN FRONT OF SAIDBULB INCLUDING A PAIR OF SUBSTANTIALLY INDENTICAL SEMI-CYLINDRICALSHUTTERS IN SPACED PARALLEL RELATION TO SAID HORIZONTAL AXIS OF THE BULBAND HAVING ADJACENT VERTICAL EDGES, SAID SHUTTERS BEING SLIDABLY MOUNTEDON A SINGLE HORIZONTAL AXIS IN SAID HOUSING FOR MOVEMENT TOWARD AND AWAYFROM EACH OTHER SO AS TO DEFINE AN ADJUSTABLE SLIT OPENING BETWEEN THEADJACENT VERTICAL EDGES FOR PERMITTING THE PASSAGE OF SAID BEAM OF LIGHTIN CONFORMANCE WITH THE SIZE OF SAID SLIT OPENING.